In speeches after 9/11, Attorney General John Ashcroft talked about the need to think outside the box while staying within the Constitution. Sitting in his office at the Justice Department, Ashcroft defended the appropriateness of working with a one-time drug smuggler.

"We're very conscious of the responsibility we have to defend the American people from an attack of terrorists," says Ashcroft. "And we are not in the business of disqualifying technology by the author. We are in the business of using technology based on its ability to help the American people."

Remember the program Hank Asher created after 9/11, the one that combed through huge criminal and commercial databases to find people with certain telling characteristics? Over the following months, Asher and Seisint developed that program into something eventually dubbed Matrix.

"Just to run it makes me excited," says Asher. "To know that we built it? Just blows me away. It's a beautiful piece of technology. It's a thousand beautiful pieces of technology connected together in a very smart way."

What does Matrix do? An investigator sits down at a computer and types in fragments of evidence about a suspect - hair color, a digit or two from a license plate, maybe a history of flying to a certain foreign country. Within seconds, up pops a driver's license photo along with a rich dossier: all the suspect's addresses, past and present; the vehicles he's owned; and business and financial information.

The company Asher started, Seisint, refused to show the system to reporters, but those who've seen Matrix tend to rave.

"It certainly is brand new; it certainly has a capability that did not exist before," says Steve Lauer, chief of domestic security for the state of Florida. The state teamed with Asher in creating Matrix and promoting it to other state governments. Lauer says what's new about Matrix is how it allows an investigator to dip into vast oceans of both commercial data and police records.

"It is a tool that allows him to cut to the chase," says Lauer, "cut to the core issue of ... the right-size guy, the right kind of background, the right kind of address, and focus on him. And I think that's what blows people away."

But more than that, Matrix and a growing number of other commercial systems find links among people. So the digital dossier may also include photos and records of the suspect's family and neighbors, even long-forgotten associates. Investigators can tell Matrix to choose suspects based on the kinds of relationships they have - for example, a roommate with a Muslim-sounding name. A human investigator could spend months and never see such links. With Matrix, it takes an instant.

Authorities believe this kind of technology could be the key to helping connect the dots. Civil liberties advocates say there's one big problem.

"What it depends upon is millions and billions of bits of information about innocent people engaging in innocent daily activities," says James Dempsey, head of the Center for Democracy and Technology in Washington, D.C.

He argues that data mining tools like Matrix, in effect, create new information by giving investigators the power to discern patterns and apply profiles. And they do so by scanning personal records about almost everybody. "It's an electronic door-to-door search," says Dempsey. He agrees that Matrix and similar networks can help protect the country. But he says a hodgepodge of laws places too few restraints on the data industry.

"What are the limits, what are the standards, the guidelines, the mechanisms for accountability, for redress? How do you even know where to call ... to ask, 'What does Matrix have about me?'"